1. Field of the Invention
The present invention relates to a method and apparatus for processing a polysilazane film disposed on a target substrate, such as a silicon wafer.
2. Description of the Related Art
In general, a silicon oxide film (SiO2 film) is used as an insulating film, such as a device isolation film or inter-level insulating film, for semiconductor devices. As methods of forming a silicon oxide film of this kind, a BPSG (Boron Phospho-Silicate Glass) method, ozone TEOS (TetraEthyl Ortho-Silicate) method, USG (Undoped Silicate Glass) method, and HDP (High Density Plasma enhanced chemical vapor deposition) method are known.
In recent years, semiconductor devices have become smaller with the increase in integration, thereby increasing the aspect ratio of trenches for STI (Shallow Trench Isolation) and recesses, e.g., gaps between members thereof. Where a method, such as BPSG method, ozone TEOS method, or HDP method, as described above, is used to form an SiO2 film to fill a recess having a high aspect ratio, a problem arises such that the SiO2 film is very poor in filling the recess (step coverage).
In order to improve the step coverage for a recess having a high aspect ratio, it has been researched to use a polysilazane film as a device isolation film or inter-level insulating film. Where a polysilazane film is formed, a polysilazane coating solution is applied onto a target substrate, and is then subjected to a heat process, thereby forming a polysilazane film.
Jpn. Pat. Appln. KOKAI Publication No. 10-321719 (see Paragraph No. 0077) discloses a method of forming a polysilazane film of this kind. According to this method, a film of polysilazane coating solution is subjected to a first heat process at a temperature of from 100° C. to 250° C. to vaporize its organic solvent. Then, the film is subjected to a second heat process at a temperature of 550° C. or less, such as 400° C., to cure the film, thereby forming a polysilazane film or insulating film. However, in practice, where this method is used to form a polysilazane film, the film is brittle and therefore difficult to use as a device isolation film or inter-level insulating film.